The present invention generally relates to ultrasound imaging catheters. The present invention further relates to transesophageal echocardiographic catheters for the purpose of guiding cardiac interventions. The present invention still further relates further to intracardiac echocardiographic catheters for the purpose of guiding cardiac interventions.
Atrial fibrillation (AF) is the most common arrhythmia in the United States and other developed countries. Nearly two (2) million individuals in the United States have AF. Catheter ablation is increasingly selected therapy for AF. Radiofrequency ablation is the most common form of AF ablation.
AF ablation procedures are however not without serious risks. Such risks include the formation of atrio-esophageal fistulas and thrombus. Successful outcome of RF ablation procedures depends in part on the contiguity and transmurality of the ablative lesions and is largely dependent on the skill of the operator.
Image guidance techniques such as fluoroscopy, electroanatomic mapping (EAM), and echocardiography facilitate such procedures. These existing technologies however have important limitations. Fluoroscopy provides a two-dimensional view of external structures, has poor soft tissue contrast, requires the injection of contrast, and exposes the patient and staff to radiation. EAM is useful for mapping the electrical properties of the left atrial wall and pulmonary veins in order to determine the location of the susceptible substrates and focal triggers that support AF. EAM is often combined with catheter tracking technologies to facilitate catheter positioning. However, EAM is time consuming, complex, and does not provide real-time imaging of cardiac tissue. Further, registration can be lost due to cardiac motion. Intracardiac echocardiography (ICE) is the most commonly used ultrasound-based technique for AF ablation image guidance. However, ICE catheters are practically limited to imaging from the right atrium due to their relatively large size. This leads to relatively poor image performance, particularly for key cardiac structures such as the left pulmonary veins. Transesophageal echocardiography (TEE) enables imaging of the left atrium from the esophagus. However, relatively poor near-field resolution of current TEE probes makes imaging of important cardiac structures difficult, such as the left atrium posterior wall. Further, TEE often requires general anesthesia due to patient discomfort from large probe size.
In view of the limitations to image guidance technologies for AF ablation noted heretofore, there is a need in the art for real-time visualization of the left atrium posterior wall and pulmonary veins, pre-intervention mapping of susceptible substrates, ablation lesion assessment, and the ability to mitigate complications.